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Asteroid Dust Confirms Meteorites’ Origins

The Hayabusa capsule, a spacecraft launched by the Japan Aerospace Exploration Agency in 2003, landed in South Australia.Credit
JAXA/ISIS

Last year, a Japanese spacecraft brought asteroid dust back to Earth for the first time, and now researchers analyzing the dust report that most meteorites on Earth originate from stony S-type asteroids like the one sampled, confirming what scientists have long theorized, but had never been able to prove.

Through actual, physical sampling of the dust particles, less than four thousandths of an inch in length, researchers were able to confirm that the dust is identical to material that makes up meteorites.

An Itokawa dust particle viewed under an optical microscope.Credit
JAXA/ISIS

The asteroid dust was gathered by Hayabusa, a spacecraft launched by the Japan Aerospace Exploration Agency in 2003. It arrived on the surface of an S-type asteroid known as Itokawa more than two years later, and then re-entered the Earth’s atmosphere and landed in southern Australia last summer.

Meteorites that hit the Earth are thought to be among the oldest objects in the solar system, and the research confirms that S-type asteroids are also ancient, said Tomoki Nakamura, a scientist at Tohoku University in Sendai, Japan, and an author on each of the studies.

They are “primitive planetary bodies that record the history of the early solar system,” Dr. Nakamura said.

He and his colleagues made a number of other discoveries about the asteroid. They believe that the dust had been lying on the asteroid’s surface for about eight million years. They also suggest that Itokawa originated from a larger asteroid.

A version of this article appears in print on August 30, 2011, on Page D3 of the New York edition with the headline: Asteroid Dust Confirms Meteorites’ Origins. Order Reprints|Today's Paper|Subscribe